A composite wear-resistant superhydrophobic coating and its usage method

Abstract

The present invention discloses a composite wear-resistant superhydrophobic coating and a method for using the same. The composite wear-resistant superhydrophobic coating is composed of a surface layer material and a bottom layer material stacked. The bottom layer material includes a mixture of fluorocarbon resin and epoxy resin; the surface layer material includes hydrophobic modified ceramic microspheres, hydrophobic modified nanocellulose coated on the surface of the hydrophobic modified ceramic microspheres, and hydrophobic modified nanocellulose filled inside the hydrophobic modified ceramic microspheres; it has good superhydrophobic performance, strong adhesion, high hardness, and strong scrub resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of coatings, and in particular to a composite wear-resistant superhydrophobic coating and a method for using the same. Background Art

[0002] Nanocellulose is a new type of nano-biological material with a small fiber diameter, a large aspect ratio, and a large number of hydroxyl groups on the surface; it can form a gel with a stable three-dimensional network structure through physical entanglement and binding. The aerogel prepared therefrom not only has the characteristics of traditional aerogels, but also incorporates some properties of nanocellulose: a large specific surface area and chemical stability, good biocompatibility and degradability. The numerous hydroxyl groups on the surface make the nanocellulose aerogel extremely easy to absorb moisture, thereby causing the collapse of the aerogel structure and limiting the application of the aerogel material.

[0003] Currently, aiming at the defects of nanocellulose, based on the properties of the hydroxyl groups of nanocellulose, various functional groups can be introduced through reactions such as esterification, alkylation, and amidation to modify nanocellulose, and many nanocellulose functional materials with excellent properties can be prepared. Currently, in terms of hydrophobic modification, silylation of nanocellulose is a commonly used method.

[0004] However, there are still many problems in the current hydrophobic modification of nanocellulose alone. For example, the roughness of the coating is not high, the hydrophobic performance is not strong, and it fails to meet the superhydrophobic performance standard; there are many problems in terms of washability resistance, coating hardness, green environmental protection, etc. In particular, nanocellulose is brittle and easily forms a powder state and cannot effectively adhere to the coating surface, is easy to fall off, and has weak weather resistance, etc. Summary of the Invention

[0005] In view of this, the present application provides a composite wear-resistant superhydrophobic coating and a method for using the same, which have good superhydrophobic performance, strong adhesion, high hardness, and strong washability resistance.

[0006] To achieve the above technical purpose, the present application adopts the following technical solutions:

[0007] In a first aspect, the present application provides a composite wear-resistant superhydrophobic coating, which is composed of a surface layer material and a bottom layer material stacked. The bottom layer material includes a mixture of fluorocarbon resin and epoxy resin; the surface layer material includes hydrophobic modified ceramic microspheres, hydrophobic modified nanocellulose coated on the surface of the hydrophobic modified ceramic microspheres, and hydrophobic modified nanocellulose filled inside the hydrophobic modified ceramic microspheres.

[0008] Preferably, in the bottom layer material, the mass ratio of the fluorocarbon resin to the epoxy resin is 1-3:1.

[0009] Preferably, the preparation method of the surface layer material is as follows: Soak the hydrophobically modified ceramic microbeads in the hydrophobically modified nanocellulose solution, let it stand, then freeze, dry and grind to obtain.

[0010] Preferably, the preparation method of the hydrophobically modified ceramic microbeads is as follows: Mix the dodecafluoroheptylpropyltrimethoxysilane solution with the ceramic microbead solution to obtain.

[0011] Preferably, the preparation method of the hydrophobically modified nanocellulose is as follows: Drop the acid solution of the hydrophobizing agent into the suspension of nanocellulose, then continue to add the amine-based silane coupling agent and disperse it by ultrasonic wave to obtain the hydrophobically modified nanocellulose solution.

[0012] Preferably, the hydrophobizing agent includes one or more of cetyltrimethoxysilane, hexamethyldisilazane, alkoxysilane, chlorosilane, epoxy silane, vinyl silane.

[0013] Preferably, the pH value of the acid solution of the hydrophobizing agent is 3 - 4.

[0014] Preferably, the nanocellulose includes one or more of purified rice husk nanocellulose, purified peanut shell nanocellulose, purified coconut shell nanocellulose.

[0015] In the second aspect, the present application provides a usage method of the composite wear-resistant superhydrophobic coating, including the following steps: Spin-coat the bottom layer material on the surface of the substrate, then spray the surface layer material, and heat and age it.

[0016] Preferably, the substrate is an aluminum alloy substrate.

[0017] Preferably, the temperature of heat aging is 50 - 60 °C.

[0018] The beneficial effects of the present application are as follows:

[0019] In the present application, by compounding two materials, namely hydrophobically modified ceramic microbeads and hydrophobically modified nanocellulose, the surface layer material is obtained. In this surface layer material, the hydrophobically modified nanocellulose can not only fill the inside of the hydrophobically modified ceramic microbeads but also coat the surface of the hydrophobically modified ceramic microbeads, greatly reducing the surface energy of the coating. In addition, the compounding of the hydrophobically modified ceramic microbeads and the hydrophobically modified nanocellulose improves the roughness of the coating, and the two cooperate to improve the hydrophobic property and hardness of the coating; the surface layer material solves the problem that due to the roughness of the surface layer material, it is easy to be passivated after being corroded by acid and alkali and worn, and the superhydrophobic property is easy to be lost. The surface layer material of the present application protects the roughness of the coating surface and ensures the service life of the coating.

[0020] The fluorocarbon resin of the bottom layer material of the present application can reduce the surface energy of the coating and improve the hydrophobic property, and the epoxy resin can strengthen the adhesion to the substrate. Description of the Drawings

[0021] Figure 1 This is the test result of the coating's scrub resistance. Detailed implementation manners

[0022] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0023] Nanocellulose has excellent mechanical properties, relatively excellent moisture and heat resistance, and can be used as a coating raw material. However, the structure of the nanocellulose aerogel is relatively brittle. At the same time, a large number of hydroxyl groups are contained on the nanocellulose, and the hydroxyl groups have water absorption, so hydrophobic modification is required; at the same time, the structure of the nanocellulose aerogel is relatively brittle and is easily in the form of powder, and the powder is easy to fall off and cannot be effectively fixed on the material surface.

[0024] As a new type of non-metallic hollow multifunctional material, ceramic microspheres have characteristics such as ultra-light weight, good suspension, high hardness, high wear resistance, and chemical stability, and are widely used in many fields such as coatings, plastics, rubber ceramics, papermaking, refractory materials, and cosmetics; however, the particle size of ceramic microspheres is relatively large, the roughness is not high, and the hydrophobicity is not strong; in the superhydrophobic modification, it is necessary to ensure that the material surface has a certain roughness, but the rough surface is easily passivated after being corroded by acid and alkali and worn, and the superhydrophobic performance is easily lost.

[0025] Based on this, this application was created.

[0026] This application provides a composite wear-resistant and superhydrophobic coating. The composite wear-resistant and superhydrophobic coating is composed of a surface layer material and a bottom layer material stacked. The bottom layer material includes a mixture of fluorocarbon resin and epoxy resin; the surface layer material includes hydrophobic modified ceramic microspheres, hydrophobic modified nanocellulose coated on the surface of the hydrophobic modified ceramic microspheres, and hydrophobic modified nanocellulose filled inside the hydrophobic modified ceramic microspheres. The mass ratio of the mixture of fluorocarbon resin and epoxy resin: hydrophobic modified ceramic microspheres: cellulose aerogel powder is 35:45:20.

[0027] This application combines two materials, hydrophobic modified ceramic microspheres and hydrophobic modified nanocellulose, to obtain a surface layer material. In this surface layer material, the hydrophobic modified nanocellulose can not only fill the inside of the hydrophobic modified ceramic microspheres but also coat the surface of the hydrophobic modified ceramic microspheres, greatly reducing the surface energy of the coating. In addition, the combination of the hydrophobic modified ceramic microspheres and the hydrophobic modified nanocellulose improves the roughness of the coating, and the two cooperate to improve the hydrophobic performance and hardness of the coating; the surface layer material of this application solves the problem that it is easily passivated after being corroded by acid and alkali and worn, and the superhydrophobic performance is easily lost.

[0028] In the base material of this application, fluorocarbon resin can reduce the surface energy of the coating, improve the hydrophobic property, and enhance the adhesion to the substrate.

[0029] The mass ratio of fluorocarbon resin to epoxy resin is 1 - 3:1. Fluororesin also has a lower surface energy, greatly increasing the hydrophobic property of the coating, while epoxy resin also solves the problem that fluorocarbon resin is prone to peeling on metal substrates.

[0030] The preparation method of the surface layer material is as follows: Soak the hydrophobic modified ceramic microspheres in the hydrophobic modified nanocellulose solution, let it stand, then freeze, dry, and grind to obtain it. After freeze-drying treatment, a hydrophobic nanocellulose aerogel will form on the surface of the hydrophobic modified ceramic microspheres. At the same time, due to the soaking treatment, the hydrophobic modified ceramic microspheres and the hydrophobic modified nanocellulose are fully fused, so that after freeze-drying, a part of the hydrophobic modified nanocellulose enters the interior of the hydrophobic modified ceramic microspheres. In the surface layer material, the hardness of the single hydrophobic modified nanocellulose is not strong and it is easy to fall off after rinsing. Although the single hydrophobic modified ceramic microspheres have been hydrophobically modified, their hydrophobic property still needs to be improved. After the two are compounded, they can synergistically improve the hydrophobic property and erosion resistance of the base material.

[0031] The preparation method of the hydrophobic modified ceramic microspheres is as follows: Mix the dodecafluoroheptylpropyltrimethoxysilane solution with the ceramic microsphere solution to obtain it.

[0032] The preparation method of the hydrophobic modified nanocellulose is as follows: Drop the acid solution of the hydrophobic modifier (any one or several of cetyltrimethoxysilane, hexamethyldisilazane, alkoxysilane, chlorosilane, epoxy silane, vinyl silane) into the suspension of nanocellulose, and then add an amine silane coupling agent for ultrasonic dispersion to obtain the hydrophobic modified nanocellulose solution. In this solution, in addition to realizing the hydrophobic modification of nanocellulose, the adhesion between the cellulose aerogel powder and epoxy resin can also be improved after adding the amine silane coupling agent. The reason is that on the one hand, the amine silane coupling agent can firmly bind with a small amount of hydroxyl groups in the hydrophobically modified cellulose through chemical bonds. On the other hand, the amine silane coupling agent can also bind with the epoxy resin of the base material, so that the surface layer material can be firmly fixed on the base material, enhancing the adhesion and scrub resistance of the coating. Appropriately but not restrictively, the product number of the amine silane coupling agent is HD-M8173.

[0033] The nanocellulose includes one or several of purified nanocellulose from rice husks, purified nanocellulose from peanut husks, and purified nanocellulose from coconut husks. Using rice husks, peanut husks, and coconut husks as raw materials is green, environmentally friendly, low-cost, and highly recyclable. The preparation method is as follows: After degreasing, delignifying, and removing hemicellulose from the raw materials, nanocellulose is obtained. Taking the purified nanocellulose from peanut husks as an example, the preparation method is as follows: Take peanut husks as raw materials, wrap them with filter paper and put them into a Soxhlet extractor. Prepare a benzene-ethanol solution according to a volume ratio of 2:1, and treat it at a constant temperature of 90 °C for 6 h to remove crude fat. After taking it out, let it air dry naturally. The air-dried sample is stirred with 8% hydrogen peroxide solution at 50 °C for 8 h, and the powder is rinsed with deionized water until it reaches a neutral state. Then, an acidic condition is adjusted according to the acetic acid ratio with a pH value of 4-5, and 2% sodium chlorite is added at a constant temperature of 75 °C for a secondary treatment for 4 h. After the treatment, the powder is rinsed with deionized water again to remove most of the lignin. Treat it with hydrogen peroxide once again following the previous steps. Prepare a 2% sodium hydroxide solution (solid-liquid ratio of 1 g∶20 mL) and soak the sample at room temperature for 24 h to completely remove the hemicellulose in the powder, and rinse it with deionized water. Finally, treat it with hydrogen peroxide and wash it to neutral to ensure that the lignin can be completely removed, and purified nanocellulose from peanut husks is obtained. Put the purified nanocellulose from peanut husks into an ultrasonic cell disruptor and process it for 1 h (20 min each time), and finally obtain nanocellulose for standby.

[0034] The present application provides a method for using a composite wear-resistant superhydrophobic coating, including the following steps: Spin-coat the bottom layer material on the surface of the substrate, then spray the top layer material, and heat and age it.

[0035] The substrate is an aluminum alloy substrate. The aluminum alloy substrate can be combined with the bottom layer material of the present application through chemical bonds to improve the adhesion between the coating and the substrate.

[0036] The temperature for heat aging is 50-60 °C.

[0037] The following further illustrates this solution through specific embodiments.

[0038] Example 1

[0039] A composite wear-resistant superhydrophobic coating includes a top layer material and a bottom layer material. The bottom layer material includes a mixture of fluorocarbon resin and epoxy resin; the top layer material includes hydrophobic modified ceramic microspheres and hydrophobic modified nanocellulose coated on the surface of the hydrophobic modified ceramic microspheres and filled inside the hydrophobic modified ceramic microspheres.

[0040] Among them, the preparation method of the top layer material is as follows: Mix fluorocarbon resin and epoxy resin according to a mass ratio of 3:1 = 1:1 and set aside.

[0041] The preparation method of the surface layer material is as follows: Dissolve nanocellulose in deionized water to prepare a solution with a concentration of 1% (mass fraction), and after ultrasonic treatment for 30 min, adjust the pH of the solution to 4 with 0.1 mol / L hydrochloric acid to obtain a nanocellulose suspension; Dissolve vinyl silane as a hydrophobic modifier in deionized water to prepare a solution with a concentration of 0.5%, and after ultrasonic treatment for 30 min, adjust the pH of the solution to 4 with 0.1 mol / L hydrochloric acid. Drop 50 ml of the acid solution of the above vinyl silane into 100 ml of the nanocellulose suspension, then add 50 ml of the amine silane coupling agent HD-M8173, stir at room temperature for 3 h, and then perform ultrasonic dispersion for 5 min to obtain a hydrophobically modified nanocellulose solution; Add 1 g of ceramic microspheres to 100 ml of a 1% solution of dodecafluoroheptylpropyltrimethoxysilane to obtain hydrophobically modified ceramic microspheres; Immerse the hydrophobically modified ceramic microspheres in the hydrophobically modified nanocellulose solution, let it stand for 1 h, then pour it into a mold, place it in a refrigerator and freeze for 20 h, and then place it in a freeze dryer at -70 °C for freeze-drying treatment, and then grind it into powder to obtain the surface layer material.

[0042] Example 2

[0043] A usage method of a composite wear-resistant superhydrophobic coating includes the following steps: Spin-coat the bottom layer material on the surface of an aluminum alloy substrate, repeat the spin-coating 3 times to obtain a bottom layer with a thickness of 10 μm; Then evenly spray the surface layer material on the surface of the bottom layer material, heat and age at 50 °C for 3 h, and the composite wear-resistant superhydrophobic coating is formed into a composite wear-resistant superhydrophobic coating.

[0044] Comparative Example 1

[0045] A composite wear-resistant superhydrophobic coating, other contents are the same as those in Example 1, the difference is that the surface layer material does not include hydrophobically modified ceramic microspheres.

[0046] Comparative Example 2

[0047] A composite wear-resistant superhydrophobic coating, other contents are the same as those in Example 1, the difference is that the surface layer material does not include hydrophobically modified nanocellulose.

[0048] Comparative Example 3

[0049] A composite wear-resistant superhydrophobic coating, other contents are the same as those in Example 1, the difference is that the bottom layer material does not include fluorocarbon resin.

[0050] Comparative Example 4

[0051] A composite wear-resistant superhydrophobic coating, other contents are the same as those in Example 1, the difference is that the bottom layer material does not include epoxy resin.

[0052] Comparative Example 5

[0053] A composite wear-resistant superhydrophobic coating, the other contents are the same as those in Example 1, the difference is that it does not include the bottom layer material.

[0054] Evaluation test

[0055] The composite wear-resistant superhydrophobic coatings obtained in Example 1 and Comparative Examples 1-5 were spin-coated on the surface of an aluminum alloy substrate according to the method of Example 2 to obtain coatings, and the hydrophobic ability of the coatings is shown in Table 1, the hardness is shown in Table 2, and the scrub resistance is as Figure 1 shown, and the adhesion is shown in Table 3.

[0056] Among them, the test methods for hydrophobic ability, hardness, and scrub resistance are as follows:

[0057] Contact angle measurement: Test according to the method of static contact angle in GB / T 30447-2013;

[0058] Pencil hardness (scratch) measurement: Test according to the method of GB / T 6739-2006;

[0059] Scrub resistance test: Test according to the specified method of GB / T 9266-2009;

[0060] Adhesion test (cross-cut method): Test according to the method of GB / T 9286.

[0061] Table 1 Contact angle measurement results

[0062]

[0063] From the results in Table 1 and the comparison of contact angles, it can be seen that from Example 1, Comparative Example 1 and Comparative Example 2, there is a synergistic effect between the modified nano-cellulose aerogel powder and the hydrophobic modified ceramic microspheres. The hydrophobic modified nano-cellulose aerogel powder can not only wrap the surface of the ceramic microspheres but also fill the inside of the ceramic microspheres, and the static hydrophobic angle can reach about 160 degrees, showing superhydrophobic performance.

[0064] Table 2 Hardness test results

[0065] Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Pencil hardness (scratch) 6H 4H 6H 6H 6H 2H

[0066] It can be seen from Table 2 that the coating of the present application has high hardness, and the hydrophobic modified ceramic microspheres and the bottom layer material of the present application are beneficial to improving the hardness of the composite coating.

[0067] Table 3 Adhesion test results

[0068] Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Adhesion test (cross - hatch method) Grade 0 Grade 0 Grade 0 Grade 0 Grade 2 > Grade 5

[0069] As can be seen from Table 3, in the adhesion test of the coating of the present application, the adhesion can reach Grade 0, which proves that the coating can effectively bind to the substrate and ensure that the surface layer material will not fall off. From Figure 1 it can be seen that the coating of the present application has stronger scrub resistance compared to the coating of the comparative example.

[0070] The above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A composite wear-resistant superhydrophobic coating, characterized in that, The composite wear-resistant superhydrophobic coating is composed of a surface layer material and a bottom layer material stacked. The bottom layer material includes a mixture of fluorocarbon resin and epoxy resin; the surface layer material includes hydrophobic modified ceramic microspheres, hydrophobic modified nanocellulose coated on the surface of the hydrophobic modified ceramic microspheres, and hydrophobic modified nanocellulose filled inside the hydrophobic modified ceramic microspheres; the preparation method of the surface layer material is: soaking the hydrophobic modified ceramic microspheres in the hydrophobic modified nanocellulose solution, standing, freezing, drying, and grinding to obtain; the preparation method of the hydrophobic modified ceramic microspheres is: mixing a solution of dodecafluoroheptylpropyltrimethoxysilane with a ceramic microsphere solution to obtain; the preparation method of the hydrophobic modified nanocellulose solution is: dropping an acid solution of a hydrophobic modifier into a suspension of nanocellulose, and then adding an amine-based silane coupling agent and ultrasonically dispersing to obtain a hydrophobic modified nanocellulose solution; the hydrophobic modifier includes one or more of hexadecyltrimethoxysilane, hexamethyldisilazane, chlorosilane, epoxy silane, and vinyl silane.

2. The composite wear-resistant superhydrophobic coating according to claim 1, characterized in that, In the bottom layer material, the mass ratio of the fluorocarbon resin to the epoxy resin is 1-3:

1.

3. The composite wear-resistant superhydrophobic coating according to claim 1, characterized in that, The pH value of the hydrophobic modifier is 3-4.

4. A method for using a composite wear-resistant superhydrophobic coating according to any one of claims 1-3, characterized in that, It includes the following steps: Spin-coating the bottom layer material on the surface of the substrate, and then spraying the surface layer material and heating and aging.

5. The method for using the composite wear-resistant superhydrophobic coating according to claim 4, characterized in that, The substrate is an aluminum alloy substrate.

6. The method for using the composite wear-resistant superhydrophobic coating according to claim 4, wherein The temperature of the heating and aging is 50-60 °C.

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